Second Life is an online virtual world, developed by Linden Lab, based in San Francisco, and launched on June 23, 2003. By 2013 Second Life had approximately 1 million regular users, according to Linden Lab, which owns Second Life. The virtual world can be accessed freely via Linden Lab’s own client programs, or via alternative Third Party Viewers. Second Life users (also called Residents) create virtual representations of themselves, called avatars and are able to interact with other avatars, places or objects. They can explore the world (known as the grid), meet other residents, socialize, participate in individual and group activities, build, create, shop and trade virtual property and services with one another. It is a platform that principally features 3D-based user-generated content. Second Life also has its own virtual currency, the Linden Dollar, which is exchangeable with real world currency. — Wikipedia